PC query problems

[ugurdogrusoz]

• 1. If you perform a PC neighborhood query with HMGS2, you get "Invalid query"? There is nothing invalid about this query. Do we perhaps get no results and interpret that as invalid?
• 2. If you perform a neighborhood query with PMVK, it takes a while to get the result but the result is not properly laid out:

According to @hasanbalci this is since we perform "draft" quality layout when results are big.

[msalihaltun]

The first point is caused by empty response body, we check for data.response.body truth value and empty strings are evaluated as false. How should we fix this? Should we go ahead as normal (i.e load nothing as expected without "invalid query" prompt) or prompt the user that an empty response was received?

[msalihaltun]

On the second point, @hasanbalci is right that we have a check in sbgnviz.js where if number of nodes or edges being loaded exceeds 3000 we use layout quality preference draft. I don't specifically know how this affects the resulting layout.

[ugurdogrusoz]

Let's properly notify the user that the response is empty rather than saying their query is invalid. Do not worry about the layout issue.

[msalihaltun]

The failing test is related to #658 (comment).